Filter products typically include a filtration media and a frame that is sized and shaped to partially enclose and support the filtration media, which framed filter can then be inserted or supported in place, based upon a particular application. Filter frames can be constructed from multiple elements that are assembled together or connected to the filtration media, such as about its perimeter, so as to provide the support and application-specific filter frame. Such frame elements are known to be made from a variety of materials, including metals, plastics, and paperboard. In the case of a rectangular filter product, for example, a rectangular filtration media is surrounded at its four sides by frame pieces that may be connected at the corners and/or connected to the four side edges of the filtration media. The majority of the filtration media is thus capable of use for its filtering ability.
These typical frame elements comprise three-dimensional elements that are sized and shaped to at least partially enclose the filtration media at its edges. The frame may comprise multiple pieces assembled by use of adhesive, welding, friction fit, snap fits, mechanical fasteners. Otherwise, the entire frame or any selective portion thereof may be made integral. That is, a frame portion comprising multiple elements made together may be provided, such as, for example, by an injection molding process. In any case, the one or more frame elements must be assembled and connected with the filtration media by an assembly process. An assembly process, as used herein, is contrasted with an in-line process where elements are brought together in a continuous manner from materials of indefinite length and by which at least an intermediate product combining the continuous materials is created. By indefinite length, it is meant that a material may be provided in many different supply forms, such as, for example, in roll form, but in any case where the length of material supplied is not specifically related to the length that would be needed for a single product application.
A continuous strip of framing material that can be manufactured as an indefinite length and converted into a filter frame is disclosed in the U.S. Pat. No. 6,406,509. Specifically, a continuous strip framing blank can be made by extrusion, the framing blank having a sidewall portion and plural tabs that extend from the sidewall portion to create a u-channel of indefinite length. This channel is then notched to form corners that may further be scored to permit easy bending of the channel at the corners of the filtration media. An important aspect of the continuous strip of framing blank material is that it may easily be made by co-extrusion techniques so that different portions of the framing blank material may have different characteristics. For example, the framing blank material may also include seals of a more flexible material than the frame sidewall and tabs, which combination of features may be made by coextruding different polymeric materials together having appropriate characteristics. To assemble such filter, the continuous strip framing material is cut into discrete frame blanks with predetermined corners and the frame blanks are wrapped about a filter media with an adhesive potting compound at an interface between the filter media and the frame channels.
U.S. application Ser. No. 2003/0172633 discloses continuous strip framing material provided in indefinite length and which is storable as a flat product capable of being wound into roll form. The continuous strip of framing material includes features to create a three-dimensional frame structure about a filtration media similar to that disclosed in U.S. Pat. No. 6,406,509. This material has the ability to make a continuous framing material, while also being in a form which can be effectively stored and supplied as a continuous framing material in a continuous in-line process.